Rib fracture is not an uncommon traumatic injury, with prognoses ranging from favorable to adverse, depending on various factors [23]. While conservative management remains the primary treatment for nonpathological or uncomplicated cases, surgical stabilization may sometimes be necessary to achieve optimal outcomes [24, 25]. With respect to conservative approaches, adequate pain management and early rehabilitation of pulmonary function, such as lung volume expansion therapy utilizing incentive spirometry, have been the focal points of care [26, 27].

Historically, thoracic epidural analgesia (TEA) has been identified as the preferred method to mitigate the pain associated with rib fractures [28]. Although previous studies have demonstrated the advantages of TEA in reducing mortality and duration of hospital stay and enhancing postoperative pulmonary ventilation, the application of this technique may be limited by its failure rate as high as 32% and adverse events related to either the medication applied or the catheter itself [29,30,31]. In fact, no obvious advantage of TEA in terms of 30-day mortality, duration of mechanical ventilation or duration of ICU stay was demonstrated, although TEA was shown to be associated with prolonged length of hospitalization [31, 32], all of which have led to a search for better analgesic methods while minimizing complications. The efficacy of various regional anesthetic techniques, including thoracic paravertebral block (TPVB), intercostal nerve block (INB), serratus anterior block (SAB) and ESPB, as components of the MMA for the management of rib fractures has been demonstrated. TPVB has been shown to be as efficacious as TEA in SSRF, with a lower incidence of hypotension and urinary retention [33]. INB also has a superb analgesic effect and improves respiratory function [34, 35]; however, INB may be limited by its analgesic duration and risk of pneumothorax and often requires multilevel injections [29, 36, 37]. Similarly, SAB has been demonstrated to have an analgesic effect on the blockade of thoracic intercostal nerves T2–T9 without multilevel injections; however, its analgesic effect on only the anterior two-thirds of the chest wall has limited its use for posterior rib fractures [36, 38,39,40,41,42,43]. ESPB has gained popularity recently for fewer technique-related complications and its versatility across a spectrum of surgical procedures [12, 44, 45]. ESPB was shown to be noninferior to TEA, with additional benefits in terms of reduced adverse events, better arterial oxygenation and pulmonary function, in addition to a lower visual analog scale (VAS) score and a more stable MAP [46,47,48]. Moreover, ESPB appears to have a shorter learning curve with a higher success rate among trainees [19, 49, 50]. ESPB may therefore serve as the preferred choice as part of the MMA protocol in rib fracture-related pain, without limitations and complications associated with TEA. ESPB showed comparable efficacy to TPBV in reducing pain scores and opioid consumption, but the incidence of hypertension was greater with TPVB, while TPVB may lead to a steeper learning curve and a greater complication rate of pneumothorax in clinical application [50,51,52]. Other novel techniques, such as retrolaminar block, rhomboid intercostal block, midpoint of transverse process block and parascapular subiliocostalis plane block, have emerged as potential alternatives; nevertheless, the evidence remains insufficient [25, 36, 37].

Despite nonoperative fracture treatment for these patients, the absence of immediate rib stabilization may leave some patients at risk of delayed complications, such as rib displacement, atelectasis, and hemopneumothorax [53]. Therefore, it is imperative that physicians remain vigilant throughout the course of initial management. Patients complicated with different conditions may require surgical intervention, and the indications for surgical stabilization of rib fractures (SSRFs) include shock or ongoing resuscitation, severe traumatic brain injury, fractures outside of ribs three to ten and acute myocardial infarction on the basis of the guidelines published by the Chest Wall Injury Society [54]. SSRF has been proven to shorten the length of hospital stay, prevent further infection and improve overall outcomes [55, 56]. The efficacy of preemptive nerve block prior to surgery remains a subject of interest. Nerve blocks have become a commonly performed intervention before surgical procedures, with the aim of mitigating surgical stress, as abrupt changes in hemodynamics, particularly heart rate, have been correlated with significant pain secondary to sympathetic activation [57, 58]. Traditionally, opioids have been employed to maintain hemodynamic stability in response to these physiological perturbations. However, such utilization is associated with a spectrum of adverse effects, such as postoperative nausea and vomiting, respiratory depression, and delayed recovery from anesthesia [59,60,61]. Consequently, a multitude of methodologies have been employed in the domain of anesthesia to reduce the reliance on opioid drugs.

In our study, we demonstrated that preemptive ESPB may provide adequate analgesia in response to surgical stress and reduce hemodynamic fluctuations and opioid requirements in SSRF. To the best of our knowledge, this is the first study to evaluate the effects of ESPB on intraoperative hemodynamics and its analgesic efficacy in SSRF. Consistent with the literature discussing abdominal surgeries, mastectomies and thoracoscopic surgeries [20, 58, 62], statistical analysis of hemodynamics revealed a relatively stable and lower HR, SBP, and MAP in a linear trend in the ESPB group than in the control group throughout the 90-minute intraoperative period after adjustment for age and intraoperative opioid consumption. These results suggest that ESPB has a beneficial effect on stabilizing intraoperative hemodynamics and controlling pain. Postoperatively, although no difference in opioid requirements was observed between the ESPB and control groups, ESPB consistently requires fewer simple analgesics on postoperative days 1 and 2, demonstrating that the efficacy of preemptive ESPB may have an effect on acute surgical pain postoperatively. Therefore, these findings suggest that ESPB produces prolonged hemodynamic stabilization and analgesic effects during the perioperative period. Together with the positive results from our study, ESPB appeared promising because of its ability to stabilize hemodynamics and analgesic effects on SSRF.

There were several limitations in our study. First, due to the nature of retrospective study, selection bias could not be entirely excluded. Whether the patients received ESPB or not were not randomized, respecting patients’ choices after they were fully explained on the risks and benefits of ESPB. Secondly, there was a lack of standardized protocol for the use of anesthetics and analgesics during the perioperative period. Thirdly, complications such as postoperative nausea and vomiting, constipation and gastrointestinal symptoms were not adequately documented in the electronic medical records. Furthermore, information on the degree of displacement of rib fractures or type of surgery was not obtained due to the lack of information on the operation record. Lastly, long term outcome of SSRF with or without ESPB was not assessed. That said, to minimize biases, only patients of the same surgical team with similar surgical techniques and postoperative care practices were included in the study and ESPB was also performed by a group of anesthesiologists dedicated to the Acute Pain Service for all these patients. Although the present study has established practical implications of ESPB for SSRF perioperatively, future larger prospective studies are thus required to validate our results and assess long term outcomes.

We have demonstrated that with the implementation of ultrasound guidance, ESPB may be performed safely in the operating rooms. The findings of our study have provided valuable insight for anesthesiologists in executing ultrasound-guided ESPB as a preemptive analgesic to optimize intraoperative hemodynamic stability and as part of MMA for providing analgesia with opioid-sparing effects for perioperative pain management in the future.